The present invention relates to an ink-jet head assembling apparatus for assembling an ink-jet head by attaching a top plate member formed with nozzles corresponding to heaters onto a heater board formed with a plurality of heaters.
In recent years, a print head, which executes a so-called bubble-jet print operation for heating an ink to form a bubble upon ejection of the ink to be printed on a paper sheet, has been developed and put into practical applications since it is advantageous for improving print precision.
In an assembling apparatus for assembling such a bubble-jet print head, heaters for heating the ink and ejection orifices for ejecting ink bubbles obtained by heating and boiling the ink by the corresponding heaters toward a paper sheet must be precisely aligned on the micron order. More specifically, a heater board formed with a large number of heaters and a top plate comprising an orifice plate formed with a large number of ejection orifices must be aligned on the micron order. For example, in order to achieve precision as high as about 360 dpi (dots per inch) as print precision, 64 ejection orifices must be arranged at equal intervals within a range of about 4.5 mm, and the arrangement pitch in this case is as small as about 70 .mu.m.
In formation of ejection orifices at such small intervals, for example, the ejection orifices can be formed with predetermined allowable high precision on the orifice plate attached to the front surface of the top plate member using an ultra-precision working machine such as a laser working machine. In formation of heaters, the heaters can be similarly formed on the heater board with predetermined allowable high precision using an ultra-precision etching technique.
Under such circumstances, when a bubble-jet print head is to be assembled, the top plate must be placed on and fixed to the heater board in a state wherein the positions of the heaters on the heater board and the positions of the ejection orifices formed on the orifice plate precisely coincide with each other.
A conventional ink-jet head assembling apparatus for aligning a top plate with a heater board with high precision, as described above, will be described below with reference to FIG. 1.
In the conventional ink-jet head assembling apparatus shown in FIG. 1, in order to precisely align the position of a heater board 102 with the position of an orifice plate 108, a first ITV camera 440 for observing ejection orifices formed on the orifice plate 108 from the front side and a second ITV camera 442 for observing heaters on the upper surface of the heater board 102 from the above are respectively arranged in front of and above an assembling jig 416. A top plate 104 and the heater board 102 are precisely aligned on the basis of information of the positions of the ejection orifices and information of the positions of the heaters, which are respectively read by the first and second ITV cameras 440 and 442.
More specifically, in the conventional assembling apparatus, an operation for attaching the top plate 104 on the heater board 102 is performed by the following procedure. First, the second ITV camera 442 measures the position of the heater board 102. The top plate 104 comprising the orifice plate 108 is held by a hand 427, and is placed above the heater board 102. Then, the first ITV camera measures the positions of the ejection orifices of the orifice plate 108. The hand 427 precisely performs position adjustment in the x-direction (a direction perpendicular to the plane of drawing of FIG. 1) and the y-direction on the basis of position information from the first and second ITV cameras 440 and 442. In a state wherein the top plate 104 is aligned with the heater board 102, a leaf spring for fixing the top plate 104 to the heater board 102 is attached from a position above the heater board 102, thus completing the attaching operation of the top plate 104 to the heater board 102.
In the conventional assembling apparatus which performs the above-mentioned assembling operation, when the leaf spring for fixing the top plate 104 is attached to the heater board 102, if the leaf spring is attached from a position above the heater board 102 while the top plate 104 is aligned with the heater board 102 by the hand 427, the hand 427 disturbs the attaching operation of the leaf spring to the top plate 104 and the heater board 102. On the other hand, when the leaf spring is attached after the holding state of the hand 427 is released, and the hand 427 is escaped from the position above the top plate 104, since the positional relationship between the top plate 104 and the heater board 102 is not regulated at all, the top plate 104 and the heater board 102 may be displaced from each other by the attaching operation of the leaf spring.
Since the second ITV camera 442 is arranged above the top plate 102, it also disturbs the attaching operation of the leaf spring.
For this reason, in the conventional assembling apparatus, when the top plate 104 is placed on the heater board 102, a small amount of ultraviolet curing adhesive S is dropped on the heater board 102, the top plate 104 is placed thereon, and the ultraviolet curing adhesive is cured to temporarily fix the top plate 104 and the heater board 102 after adjustment of the position of the top plate 104 with respect to the heater board 102. More specifically, since the top plate 104 is temporarily fixed to the heater board 102 by the adhesive, the top plate 104 and the heater board 102 can be prevented from being displaced from each other even after the hand 427 for holding the top plate 104 in position is escaped, and also when the top plate 104 and the heater board 102 are moved to a position where they are not disturbed by the second ITV camera 442 upon attaching of the leaf spring.
However, in the conventional assembling apparatus, as described above, when the top plate 104 is attached to the heater board 102, since they are temporarily fixed by the ultraviolet curing adhesive, it takes a long time for curing the ultraviolet curing adhesive, thus lowering productivity.
Since the step of placing the top plate 104 on the heater board 102, the step of measuring the positions of the top plate 104 and the heater board 102, and the step of adjusting the position of the top plate 104 with respect to the heater board 102 are sequentially executed as well as the step of curing the ultraviolet curing adhesive, long time is required for assembling one print head, and productivity is lowered. In order to compensate for the low productivity, a large number of expensive assembling apparatuses comprising a precision stage for adjusting the positions of the top plate 104 and the heater board 102, ITV cameras, and the like must be prepared, and an investment for the production line becomes costly.
In the conventional assembling apparatus, since the step of placing the top plate 104 on the heater board 102, the step of measuring the positions of the top plate 104 and the heater board 102, and the step of adjusting the position of the top plate 104 with respect to the heater board 102 are sequentially executed, long time is required for assembling one print head, and productivity is lowered.
As a method of solving this problem, the above-mentioned assembling steps may be divided, and the divided steps may be performed by different work stations. However, for example, when a first work station measures the position of the heater board 102, and a second work station aligns the position of the top plate 104 with the heater board 102, since the positions of works (the heater board 102 and the top plate 104) suffer from variations, the step of adjusting the focusing states of the ITV cameras and the step of adjusting the position of an adjusting mechanism for adjusting the position of the top plate 104 are required in accordance with the variations of the positions of the works when the works are indexed to the position of the second work station. As a result, the tact time of the assembling operation is prolonged, thus lowering productivity.